Engine-testing gauge



May 13, 1930. G. ZITZMANN 1,753,271

' ENGINE TESTING'GAUGE Originl i-"iled Feb. 8,- 1926 ll H III" n. 5

.P atented May 13, 1930 nition timing. ,The invention provides a simpleand mev UNITED STATES" PATENT OFFICE enonen zrrzlrmn, or 'vommas, NEWYonm'nssrenon r 'auromrrc' moron conr1101. conronnrron, or NEW roux-,1;Y., A conroaarron or NEW YORK Application filed February s,'19 2e,seria1' No. 86,764. Renewed m 1?, 1928.

This invention relates to engine testing gauges, and has for .its objectthe provision of a gauge that will accurately indicate compressionconditions within the cylinder and that will also show the accuracy ofthe igchanic-proof instrument that is able to stand 7 internal flange13. A coupling 14 fits the lower end of the nut and is clamped the hardwear and abuse of an automobile repair shop and that will give readingsto within very close limits. V

Other objects and advantages of the invention will becomeapparent as thedescription proceeds.

In the drawings, Fig. 'l is an elevation of the gauge'in its operativerelation to an engine cylinder;

Fig. 2. is a longitudinal section through-the gauge; Flg. 3 is across-section on line 33 of Fig. 1, parts being broken away. Referrinmore particularly to the drawings, the b0 y of the instrument is ahousin 10 composed of a main cylinder 11 to the lower end of which isthreaded anut 12 having an against the flange 13 by a sleeve 15 whichhas a shoulder engaging the upper part of the flange and a shank 16threaded within the coupling 14.

A rod 17 is slidably mounted in: the lower end of coupling 14'and hasan-ofi-set extension 18 to make contact with the top of the piston whenthe housing is inserted in a spark plug opening as shown in Fig. 1. I

Within the coupling 14 the rod 17 carries a transverse pin 19 which actsas a lower abutment for a spring 20 surrounding the rod, the upperabutment for the spring being the shoulder-21 on the upper end of sleeve15. The upper endof rod 17, which slidably passesthrough the end ofsleeve 15, is threaded and provided with an adjustable cap 22. Oneside'of rod 17 is flattened as shown at 23 and indicating marks 24 areplaced on this flat surface. A hole bottom of coupling 14. i

The gauge housing 2:6 is secured to the upper end of cylinder 11' and"carries the face 14 its movement by for longitudinal tent of the 25 ismade in the plate with a scale inscribed thereon. Two

, readingsjcooperate with the scale, one within the scale and oneoutside the scale, both read ingsstarting from zero at the left hand endof the scale. A pointer 27 cooperates with the scale and is carried by ashaft 28 j ournaled in J and 37 clamping a washer 38 between them isins'ertedfin the cylinder 11 and is limitedin the cylinder. Acompression spring 40 pressing against shoulder 41' on the cylinder nor?mally holds the piston against the stop ring.

An 1nsulating tube 42 is inserted in one side of gauge housing 26 and aspark point 43,

provided with a grooved cable hook-on 44 is mounted in a stationaryposition within said tube. A second insulating tube 45 is mounted in theopposite side of the gauge housing and carries the spark point 46 whichis mounted screw adjustment and carr1es a grooved cable hook-on 47. Awindow 48 is formed in the face plate so that the exgap between thespark points can be visually determined.-

In constructing the gauge the parts are so designed that a movement of.010 of an inch on the lower end of rod 17 will be magnified a stop ring39 mounted in and move the pointer one full division of the mnerreadings, making it possible to check the position of the piston withinveryclose limits. 7 1

The device is operated in the following manner: v

The nut 12 isunscrewed from cylinder 11, and the lower partof thehousing, which m'a i be called the contact unit, is attached to thespark plug opening of a cylinder with the offset arm 18 extending overthe top of the piston as shown in Fig. 1. The cap 22 is normally screweddown against sleeve 15 to raise pin 19 from contact with the bottom ofcoupling testing a car in which the relative position v of the top limitof piston travel is unknown. When the device is to bellsed a lim- 1tednumber of different cars, a suitably let- 'tered aduation 24 can beprovided for each n this case it wonld be necessary car. I merely to setthe cap 22 above the graduation for the car bein tested. Once cap 22 hasbeen properly a justed the cylinder 11, or housing unit, is screwed intothe nut.12 and the proper ignition wiresare attached to the hook-ons 44and 47. The motor is nowcranked until the cylinder being tested reachesits compression stroke. As the piston ascends on the compressionstrokethe gas' within the cylinder is. compressed andflows throughopening 25 and around'rod 17 into contact with the piston 36,'which"is'driven upwardly. moving the pointer away from its zeroposition. Thepistonis stopped at the top of its stroke,'atwhich time the maximumcompression within the cylinder can be read ofl' ontheouter set ofreadings. By watching the action of the pointer at this time thecondition'of the cylinder can be determined.' If the valves needgrinding the compression is lostrapidly and the pointer dropsbackquickly, whereas if the valves aretight and the rings are worn-thepointer moves back- 1 slowly. In either case the pointer drops-backuntil the piston 36 contactswith cap 22, in

which position the pointer indicates the top *point of piston travel,asshownin dotted .lines in Fig. 1.

The piston is now allowed slowly' descend on .what would be the powerstroke and the ointer is watched to check the accuracy when the'pistonis .040 in. below its top? limit,

-of t eignition timing. I the average car the spark, when fullyretarded, should occur or in the .full line position of Fig. 1, the

pointer in the meantime having moved' to its 'full line position. If theignition is 'accuratelytimed the s ark will now. jump across ing fromthis'dotted line position, indicating the top position of'the piston, toitsfull line position, indicating the position-of the piston at the'point the spark occurs. Obviouslythe mechanic making the test must knowthe ignition point for'the engine he is testing and read the gaugeaccordingly. This is easily done, since each division on the inner setof readings represents .010 in. of piston travel.

' It will be evident that this invention provides a gauge by which bothcompression and ignition timing can be expeditiouslygtested 'on asinglestroke of the engine. Both of these factors of engine efliciency areeasily read on a single scale, over which the inter moves from a common'zero at one en of the scale.)

WhatI claim is: 1-. In an engine gauge, forattachment in an'opening ofan engine cylinder, indicating means carried by said housing,arack barwithin said housing and operatively connected with said indicating meansand being the only operating member --co-operating directly with theindicating means, and operating mechanism co-operatmeans mounted withinthe housing and engine-piston actuatable means mounted within thehousing.

2. In an engme gauge, a housing adapted a housing adapted with'said rackbar,said operatin mecha- -nism comprising pressure-actuate forattachment in'an opening ofan engme cylinder, a graduated scale carriedby said housing, a movable pointer co-o eratingwlth said scale, avertically 'movab'e bar 0 eratively connected with said pointer, sa' barbeing permanently connected with said ointer and being the onlyoperating memer connectd directly with said pointer, and

operating means co-operatingwith said bar, H

said operating means comprising a .pres'sureactuated piston mountedwithln the housing and -an engine-piston-actuatable member I mountedwithin .the housing.

In testimony whereof I-afiix my 'slgnature.

' j GEORGE ZITZMANN. f

'the' spark gap, w ereas if, the spark occurs early or late that fact,as well as the extent of the'error, can be ascertained by noting thepositionof-ithe pointer at the time the spark occurs. The strength ofthe spark-can also be determined by adjusting the length of the sparkep- It is unimportant where the pointer stops in its dotted line so longas it is far enough away from zero to allow a back read-

